The Giant Metrewave Radio Telescope (GMRT), located near

Narayangaon Narayangaon is a town in the Junnar taluka of the Pune district of Maharashtra state, India. Water is abundant because of its proximity to the major dams, the western ghats, and the Sahyadri mountain range. Geography Narayangaon is located 656 ...

Pune Pune ( ; , ISO 15919, ISO: ), previously spelled in English as Poona (List of renamed Indian cities and states#Maharashtra, the official name until 1978), is a city in the state of Maharashtra in the Deccan Plateau, Deccan plateau in Western ...

in India, is an array of thirty fully steerable parabolic

radio telescope A radio telescope is a specialized antenna (radio), antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the r ...

s of 45 metre diameter, observing at metre

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

s. It is the largest and most sensitive radio telescope array in the world at low frequencies. It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the

Tata Institute of Fundamental Research Tata Institute of Fundamental Research (TIFR) is a leading research Institute under the Department of Atomic Energy of the Government of India. It is a public deemed university located at Navy Nagar, Colaba in Mumbai. It also has a centres in ...

Mumbai Mumbai ( ; ), also known as Bombay ( ; its official name until 1995), is the capital city of the Indian state of Maharashtra. Mumbai is the financial capital and the most populous city proper of India with an estimated population of 12 ...

. It was conceived and built under the direction of

Govind Swarup Govind Swarup (March 23, 1929 – September 7, 2020) was a pioneer in radio astronomy. In addition to research contributions in multiple areas of astronomy and astrophysics, he was a driving force behind the building of "ingenious, innovative ...

during 1984 to 1996. It is an

interferometric Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

array with baselines of up to . It was recently upgraded with new receivers, after which it is also known as the upgraded Giant Metrewave Radio Telescope (uGMRT).

Location

The Giant Metrewave Radio Telescope (GMRT) Observatory is located about 80 km north of

at Khodad. A nearby town is

which is around 9 km from the

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

site. The office of

National Centre for Radio Astrophysics National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...

(NCRA) is located in the

Savitribai Phule Pune University Savitribai Phule Pune University (SPPU), formerly the University of Pune, is a public state university located in the city of Pune, India. It was established in 1949, and is spread over a campus in the neighbourhood of Ganeshkhind. The uni ...

campus.

Science and observations

One of the aims for the telescope during its development was to search for the highly

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

ed 21-cm line radiation from primordial neutral hydrogen clouds in order to determine the epoch of galaxy formation in the

universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...

. Astronomers from all over the world regularly use this telescope to observe many different astronomical objects such as the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, Jupiter, exoplanets, magnetically active stars,

microquasar A microquasar, a smaller version of a quasar, is a compact region surrounding a stellar black hole with a mass several times that of its companion star, observable in sufficient details, in our own or nearby galaxy. The matter being pulled from ...

s or binary stars with a compact object (neutron star or black hole) as companion,

pulsar A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

e, supernovae remnants (SNR)

HII regions An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...

quasar A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...

radio galaxies A radio galaxy is a galaxy with giant regions of radio emission extending well beyond its visible structure. These energetic radio lobes are powered by jets from its active galactic nucleus. They have luminosities up to 1039 watt, W at radio ...

clusters of galaxies The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the ...

, cluster radio relics and halos, high-z galaxies,

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

s, Inter-galactic HI absorption lines, diffuse radio emission from filaments of galaxies, possible signs of

time-variation of fundamental constants The term physical constant expresses the notion of a physical quantity subject to experimental measurement which is independent of the time or location of the experiment. The constancy (immutability) of any "physical constant" is thus subject to ex ...

, variation of gas content with cosmic epoch,

epoch of reionisation In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the primordial universe to reionize after the lapse of the " dark ages". Detecting and studying the reionization process is ch ...

etc. . GMRT has produced an all sky survey named

TIFR Tata Institute of Fundamental Research (TIFR) is a leading research Institute under the Department of Atomic Energy of the Government of India. It is a public deemed university located at Navy Nagar, Colaba in Mumbai. It also has a centres in B ...

GMRT Sky Survey (TGSS). Nearly 90% of the sky has been imaged at the frequency of 150 MHz (wavelength 2m), with an angular resolution of 25 arc second and rms noise of 5 mili Jansky per beam. Source Catalogue and FITS image files for the scientific community are freely available. General public and citizen scientists can see 150 MHz image of any, supernova remnant, spiral galaxy or radio galaxy with its name or position at th
RAD@home RGB-maker web-tool
Power and versatility of the GMRT has led to a renaissance in the field of low frequency radio astronomy. From this, TGSS survey, data, in August 2018, the most distant known radio galaxy : TGSS J1530+1049, located at a distance of 12 billion light years, was discovered by GMRT. In February 2020, it helped in the observation of evidence of the largest known explosion in the history of the universe, the

Ophiuchus Supercluster explosion NeVe 1 is a supergiant elliptical galaxy, which is the central, dominant member and brightest cluster galaxy (BCG) of the Ophiuchus Cluster. It lies at a distance of about 411 million light-years away from Earth and is located behind the Zone ...

. In January 2023, the telescope picked up a radio signal (21 cm line emission from neutral atomic hydrogen gas) which originated from 8.8 billion light years away.

Activities

Each year on

National Science Day National Science Day is celebrated in India on February 28 each year to mark the discovery of the Raman effect by Indian physicist Sir C. V. Raman on 28 February 1928. For his discovery, Sir C.V. Raman was awarded the Nobel Prize in Physics in ...

the observatory invites the public and pupils from schools and colleges in the surrounding area to visit the site where they can listen to explanations of radio astronomy, receiver technology and astronomy from the engineers and astronomers who work there. Nearby schools/colleges are also invited to put their individual science experiments in exhibition and the best one in each level (primary, secondary school and Jr. college) are awarded. Visitors are allowed into GMRT only on Fridays in two sessions - Morning (1100 hrs - 1300 hrs) and Evening (1500 hrs to 1700 hrs).

Gallery

File:Remote closeup view of one GMRT antenna through the fields.jpg, GMRT antenna File:Plaque of GMRT at the entrance gate.jpg, Plaque of GMRT at the entrance gate File:Main administrative building of GMRT in the campus.jpg, Main administrative building of GMRT in the campus File:Backside view of GMRT C-3 antenna from the right.jpg, Backside view of GMRT C-3 antenna from the right File:New building of GMRT under construction in the campus.jpg, New building of GMRT under construction in the campus

References

External links